It is commonly known to transport fibre-reinforced polymer blades for modern wind turbines generating electricity by truck, by train or by ship. In order to include as many blades as possible at each transport, the blades are often packed upended in relation to each other. For example, three blades are often packed so that two roots are arranged at the one end interspaced by one blade tip, thus resulting in only one root and two blade tips being arranged at the other end.
Another example of a known packing method is disclosed in WO 02/083523, where the blades are arranged in frames secured at the blade root and the blade tip, respectively, and then joined with an upended blade arranged in corresponding frames. As a result, the blades may be arranged modularly close together in both the horizontal and the vertical plane.
During recent years, several wind turbine blade manufacturers have started manufacturing blades designed so that they curve away from the tower when mounted. The blade thus curves in the unloaded state in such a manner that the wind turbine blade presents a substantially concave face and a substantially convex face. The expression concave face refers to the face of the blade from which the longitudinal, geometrical centre line of the blade bents inwardly. The expression convex face refers to the face of the blade from which the longitudinal centre line of the blade bents outwardly. When the blade is mounted so that the blade tip curves away from the tower, the convex face thus faces the tower and the concave face faces away from the tower. In this way, an increased distance is ensured between the blade tip and the tower, which is desirable in order to reduce the risk of the often very long blades bending due to the wind pressure and hitting the tower during high wind. WO 99/14490 discloses such a solution.
The industry has provided examples of blades of a length of 54 meters and above being manufactured with a curvature of only approx. two meters, primarily due to the subsequent and necessary transportation from the manufacturing site to the application site/mounting site.
However, the present and increasing blade lengths have given rise to an increasing demand for the manufacture of blades with a significantly greater curvature in order to minimise or rather maintain an acceptably small projection on the nacelle.
Thus, it is also desirable to be able to transport blades having a significantly greater curvature than approx. two meters, which is hardly possible by using the known methods of transporting blades of this type to wind power plants.